Effects on airways of short-term exposure to two kinds of wood smoke in a chamber study of healthy humans

Abstract

Introduction: Air pollution causes respiratory symptoms and pulmonary disease. Airway inflammation may be involved in the mechanism also for cardiovascular disease. Wood smoke is a significant contributor to air pollution, with complex and varying composition. We examined airway effects of two kinds of wood smoke in a chamber study.

Materials and Methods: Thirteen subjects were exposed to filtered air and to wood smoke from the start-up phase and the burn-out phase of the wood-burning cycle. Levels of PM_2.5 were 295 µg/m³ and 146 µg/m³, number concentrations 140 000/cm³ and 100 000/cm³. Biomarkers in blood, breath and urine were measured before and on several occasions after exposure. Effects of wood smoke exposure were assessed adjusting for results with filtered air.

Results: After exposure to wood smoke from the start-up, but not the burn-out session, Clara cell protein 16 (CC16) increased in serum after 4 hours, and in urine the next morning. CC16 showed a clear diurnal variation. Fraction of exhaled nitric oxide (FENO) increased after wood smoke exposure from the burn-out phase, but partly due to a decrease after exposure to filtered air. No other airway markers increased.

Conclusions: The results indicate that relatively low levels of wood smoke exposure induce effects on airways. Effects on airway epithelial permeability was shown for the start-up phase of wood burning, while FENO increased after the burn-out session. CC16 seems to be a sensitive marker of effects of air pollution both in serum and urine, but its function and the significance need to be clarified.

Keywords::

• Controlled exposure
• wood smoke
• particles
• biomarkers
• humans
• health effects
• airway effects

Acknowledgments

This study was funded by the Swedish council for working life and social research (FAS), and by the Swedish Environmental Protection Agency through the Swedish Clean Air Research Program (SCARP). The authors thank Marianne Andersson, Annica Claesson (both from our own department) and Linda Bohlin at the SP for skillful technical assistance.

Declaration of interest

The authors report no declarations of interest.